Cutter sharpener



June 18, 1935.

:inventor /yl/Gtforneg June 18, 1935. M. H. HILL CUTTER SHARPENER 3 Sheets-Shet 2 Filed Dec. 8, 1932 June 18, 1935. M. H. HILL CUTTER SHARFENER .'5 Sheets-Shet Y 3 Filed Dec. 8, 1932 y QSMN @amg/ yay/ifm (Ittorneg Patented June 18, 19.35v

CUTTER SHARPENER Maxwell H. Hill, Rochester, N. Y., assignor to Gleason Works, Rochester, N. Y., a corpora-v ti'on of New York Application December s, 1932, serial No. 646,270

6 Claims.

`The' present invention relatesA to machines for sharpening cutting tools and particularly to machines for sharpening rotary millingV cutters such, asAv are' used in rough-cutting straight bevel gears.

The primary object of the present invention is to provide a disc-cutter Sharpener which will be simpler in construction and simpler and faster K in operation" thanl machines heretofore built for the purpose and' which at the same time can be used to sharpeni cutters in a wet-grinding operation.

Still another object of the invention is to provide a machine which can be changed over quickly to vpermit sharpening cutters of diierent sizes and, inA this connection, it is a further purpose' of the invention to provide a cutter Sharpener having anotched-plate type of index mechanism, in which the same index-actuating andv locking partsmay be employed regardless of the size of the cutters to be sharpened and of the' index plates used in their sharpening.

f Further objects of the invention are toprovide a disc-cutter Sharpener in which the grinding operation isI efe'ct'ed by a reciprocating movement of the grinding wheel, in which each stroke of the grinding wheel` is of suchI length as to carry the wheelclear of the cutter being ground, in which'. the cutter is indexedwhile the' cutter' is clear of the"v wheel, and in which simple' and compact means are kprovided for effecting, in timed relation the reciproc'ation of the grinding. wheel andthe indexing of the cutter,

Other objects of the4 invention are to provide ticularly the index mechanism of the present Sharpener, that may be operated as part of a closedhydraulic system withl which is incorporated simple means for vcompensating for variations in volume or pressure in the system'.

Other objects of the present invention will be apparent hereinafter' from the specicatio-n and from the recital of thel appended claims.

InY the drawings: 4 Figure 1 is a side elevation of a cutter sharpener built according to a preferred embodiment of this invention, the grinding rwheel and its supporting and operating parts beingy shown swung around to an inoperative position;

yFigure 2 is another elevational View of the machine but taken at right angles to the View of Figure 1 parts of the machine being broken away and the grinding wheel. andl associated mechanismsagain being lshown inA inoperative position. This view shows in full lines-.the po- 'l afluid-pressure operated mechanism, and par` sition which a cutter of smaller diameter than the cutter shown in Figure l would occupy when being sharpened and `indicatesin dotted lines the position which the larger diameter cutter of Figure 1 would occupy were it being sharpened. The corresponding positions of the indexing mechanism when the two cutters are being sharpened are indicated in full and in dotted lines, respectively;

Figure 3 is a View showing the cutter grinding f wheel and index mechanism in plan and showing diagrammatically the connection between the index mechanism and the hyraulic control valvel therefor, the valve being shown in section and the grinding wheel and its support being shown approximately in operative position; and

Figure 4 isa fragmentary `view showing part of the index mechanism in plan.

VIn the machine-shown in the drawings,` thev grinding wheel is mounted upon a vertically movable slide which is reciprocated by a rotary cam to passthe grinding wheel across the faces of the blades of the cutter to sharpen the same. The cutter. is mounted upon a rotatable head or support that is indexable to bring different blades of the cutter successively into position for sharpening. The indexing operationv is effected through rotation of a` n'otched index plate by a pawl that is connectedlto a piston-which is reciprocable by fluid-pressure. The movement 0I this piston is controlled from a second reciprocable piston that is operated by a rotary cam.` The two pistons form parts of a substantially closed hydraulic system which is kept filled with liquid by atmospheric pressure. This system is so arranged that, when the second piston'` is moved by its cam, this movement is transmitted through the hydraulic motive :duid to the rst piston. Thus, as the second piston is moved in opposite directions, the index mechanism will be actuated or reset, depending upon the direction of movement of the second piston. The cam for reciprocating the grinding wheel sup-V port and the cam for operating the index control piston are mounted upon the same shaft andy these cams are preferably so made that in eachv revolution of the shaft, the grinding wheel is passed back and forth across the face of a blade of the cutter and then the cutter is in dexed. The stroke of the grinding wheel support it long enough tovcarry the grinding wheel clear of the cutter so that the indexing can take place without damage to the wheel or cutter.

The indexing mechanism is of the notched plate type and the locking-dog, indexingY pawl,

' reference,

` table.

' and actuating piston are mounted upon a bracket that can be detachably secured in different` positions on the workhead of the machine to cooperate with different sized index plates.

Mechanism is provided for automatically stopping the machine when the sharpening operations on the blades or on a group of blades for cutting Yone side ofy a tooth space of a gear blank have been completed. The machine has, of course, the necessary adjustments to bring the wheel and work into operative relation. A

.Referring to the drawings by numerals of I8 designates the base orframe of the machine. The base is` formed at its upper end with an integral skirt II andwith an integral table I2 that extends upwardly above the skirt. The skirt is so spaced from the side walls of the table yas to provide a troughV I3 which is adapted to receive the coolant after use, if the machine is employed asa wet-grinder. There is a carriage I5 mounted on the table |72 and adjustable longitudinally thereon by means ofthe screw-shaft I6. This screw-shaft is mounted finthe carriage I5 and threads into a lug |1 (Figure l) formed integral with the The carriage |75 is guided in its movement by a tongue I8 which is formed on its under surface and which engages in a complementary shaped groove IQ in the upper` :face of the table. The carriage is secured in any adjusted position by T-bolts 28 whose heads engage in a T-slot 2| which is formed in the upper face of the table I I and extends longitudinaily thereof in parallelism with the groove |9 and screw-shaft I6.

Integral lugs 22 project `upwardly from the carriage |5 at either side thereof. There is a plate 24 pivotally mounted on the carriage I5. This plate 24 has a pair of integral ears 25' depending from its lower face and the plate 24 is pivotally mounted yupon the ,carriage I5 by means or" the pins 26 which connect'the ears 25 and lugs 22. The plate 24 serves as a support for the cutter to be sharpened, as will be described more particularly hereinafter.

The machine illustrated in the drawings is designed specifically for the grinding of discmilling cutters such as are commonly employed Vin the rough cutting of straight tooth bevel gears. There are two sizes of these cutters commonly in use and the machine illustrated has y been designed so that it Will sharpen both sizes of cutters, making it possible to grind on one machine cutters for which heretofore two machines would have been required.

The plate 24 yhas two circular recesses or sockets 29 and 30 formed in its upper face and the post or center 3|, that is adapted to carry the cutter,rwhich is to "be sharpened, can be secured by screws 32v in either one of these sockets, depending upon the diameter of the cutter to be sharpened. The screws 32 thread into holes 33 in the face of the plate24. Y

The cutter to be sharpened,` whether it be of large or small diameter is mounted upon an arbor 35 and this arbor in turn is mounted upon the post or center 3|. The arbor 35 hasa tapered nose which is adapted Lto enter the bore of the cutter head .and the cutter head is clamped to the arbor by a clamping-washer 31 which is secured in `position bya bolt 38 that threads into the center .or stud 3|. 39 designates a disc or washer which may be mounted upon the bolt 38 to serve as a center for an arm that carries a gage for testing the radial positions of blades secured in the cutter head. This gage forms no part of the present invention and has not been illustrated.r

In Figure 2, the post or center 3| is shown in the position it occupies when a cutter of small diameter is to be sharpened. In the drawings the cutters shown are of the inserted blade type, but it will be understood ,that the machine can be used just as well for sharpening cutters whose blades or cutting teeth are integral with the head. The small diametery cutter shown in Figure 2 includes the cutter head 40, the remov-y able cutting blades 4|, and the ring 42 and bolts 43 which secure the cuttingblades in position on the head. When such' a cutter is` being sharpened, a guard plate 45 and a notched index plate 46 both of a diameter approximately the same as that of the cutter are used. The guard plate 45 is removably secured to the arbor 35 by screws or other suitable means (not shown) and the .index plate 46 is likewise 'removably secured to the guard plate 45 by screws or other suitable means (not shown) In Figures l and 3, I have shown the center 3| in the position it occupies when a large size cutter is to be ground and we have shown a large size cutter being ground. The position of' the large size cutter is shown also,v for thesake of comparison, fragmentarilyvv in dotted lines in Figure 2. v cutter head 58, the inserted cutting blades 5I The large size cutter com'prisesthe and the Vring 52 and the bolts 53 which serve to clamp the ring and blades in position., When a large size cutter is to be ground, the index plate 46 and the guard plate45 are taken off the arbor 35 and a guard plate 55 and index plate 56 corresponding approximately in diameter to the diameter `of the large cutter are securedinstead to the arbor and the post or center 3|, having been lifted out of the socket is secured in the socket29.

Cutters are sharpened onthe present machine by grinding the front facesof the cutting blades. The grinding wheel W used for sharpening is clamped by a washer 66 and bolt 61 on a dise or plate 68 that is keyed to afspindle 60 which is journaled by means of anti-friction bearings 6| and 62 in an adjustable head 65. The discor plate 68 cooperates with a disc 69 toprovide a labyrinth seal for the front bearings 6|.A The disc 69 is secured to the head 65 by screws 10.

The head 65 is slidably adjustablev upon a carrier 15, the adjustment being effected byrrotation of the screw shaft 16 which is journaled in a bearing member 11 that is secured to the carrier 15 by screws 18. VThe shaft 16 threads into the head 65. The head slidesrectilinearly in its adjustment on the carrier 15 and can be secured in any adjusted position by T-bolts 80 which pass through the head 65 and engage in longitudinal T-slots formed in the upper face lof the carrier 15. The T-bolts 80 are manipulated bythe levers 8|. The carrier 'I5 is rotatably adjustable upon a bracket 85 that is in turn pivotally mounted upon the projecting arm 86 of a slide 8'I. This arm is of approximately semi-circular or U-shape as Vclearly shown in Figure 1 and is integral at its two ends with the body of the slide 81,

The bracket 85 has a central opening extending therethrough. The carrier 1,5 is formed with a flange that seats against the upper face of the bracket 85 and with an integral collar 88 that ts into this opening. Thus the carrier I5 is rotatably adjustable onr the bracket 85. The

motor 90 which isemployed t'o drive the grind# ing wheel spindle 60 is secured 'by bolts 9| to a plate 92 which, in turn, is secured by boltsA 93 tothe coll'ar 88.- The plate 92- seats against the underface of the bracket 85. 'Ihe motor lies beneath the bracket l85 and the arm 86 of the s1`ide-81 extends around it`.- l The carrier 1'5.' is secured in any position of its angular adjustment on the bracket 85 by bolts 94 which are mountedv in the carrier 15 and thread into the plate 92, the plate being provided with saw-slots at eitherv side yof each kbolt so that, when the bolts are threaded up, they exert a binding actionon the plate.

The motor 90 drives the grinding Wheel spindle 60 througha belt 95 which'runs on the pulley 96 thatv is secured to the'armature shaft of the motorl and' onl the pulley 9.1 which is1 keyed to the shaft 60. The pulley 91 is journaled on antifriction bearingsv 984 on a bearing member 99 that is secured. inthe head`65.

The bracket' 85v is provided with dependent arms |00L which carry pins IOI that engage in the arm 86 of' the slide 817 and form a pivotal support for the bracket 85. The bracket 8.5 is adjusted angularly about the pins 0| by the screw |04 which threads into the bracket 85 and contacts the upper face of the' arml 86.

yThe slide 81 is reciprocable upon the frame I0' of the machine for the purpose of carrying the grinding wheel W across the front faces of the blades of a cutter to sharpen the same. The slide 81 is held on the frame by the plates |05 which are secured to the frame by screws |06.

The slide 81. carries a plate |'I0 which is pivotally mounted upon a stud'` III that is threaded into the slide 81. This bracket carries a roller ||2 which' is adapted to `engage the periphery of a rotatable heart-shaped cam II'4. The roller I I2 is adjusted into contact with this cam, after bolt |I6 is released, by rotation of the screwv I I1 which is secured to the bracket I0 and which threads into` a boss |I8 that is formed' integral with the slide 81. The bolt |I6 passes'through an arcuate slot ||.9' formed in the bracket I|0 concentric to the bolt I'I and by tightening the bolt IIG, the bracket I |0` can be secured to the slide 81 against movement relative thereto.

The cam I I4 is keyed to a shaft |20 that is journaled inv the frame I0of the machine, the cam being held on this shaft by the washer' |22 andthe bolt I 23. The shaft |29 is driven by the motor |25 which is suitably mounted in the fra-me of the machine. The vworm, shaft |26l is suitably coupled tothe armature shaft of this motor and to this worm shaft |26, there isV keyed a worm |21 which meshes with a worm-wheel |28 that is keyed to the shaft I2'|l.`r The worm shaft |26 is journaled on anti-friction bearings |29 (Figure 1) in the frame of the machine.

The heart-shaped cam` |I'4 is so formed that the grinding wheel on each reciprocation of the slide 81 willbe moved clear on the cutter head. During the period that it is clear of the cutter head, the cutter head is indexed so that a new blade of the cutter is brought into position to be ground on the next stroke of the grinding wheel. The index mechanism for the cutter head will now be described.

|30 designatesa bracket which can be secured upon the plate 24' iny two different positions. When a small diameter cutter'is being `ground. and' the center' 3| is secured.' in the socket 30", the-bracket |301. is secured; to'- the' plate 24 by passing the lbolts |3| and |32, respectively, through the arcuate slots |33 and |34 which are formed in the plate 24 concentric of the socket 30. When a large cutter is to be sharpened, the bracket |30 is secured to the plate 241 by passing these same bolts |3| and |32 through the arcuate slots |35 and |36, respectively. These slots |35 and |36 are' formed concentric of the socket 29. In Figure 2, we' have shown in full lines, the position of the bracket |30 lwhen' a small size cutter is being ground, Ywhile-the, po'- sition ofV this bracket, when alarge diam'eter cutter isv bei-ng sharpened is shown in dotted lines. v` The ind-ex locking-dog I 40" is carried by the bracket |30. This dog is pivotally mounted upon a stud |4f| that is securedy in the bracket and it is constantly urged forward and into locking po- I sition by a spring pressed plunger |42' Awhich is. housed in a hole drilled in the bracket |`30. The sarne locking dog is used for both the small size index plate'46 and the large size index plate 56. The' notches in the two index plates are of the same size. Ordinarily cutters used for cutting straight tooth bevel gears' have alternate cutting blades sharpened with opposite side-cutting rakes so as to provide cutting edges on alternate blades which cut oppositeside tooth faces of a gear blank. Such cutters have been illustrated in the drawings and. for sharpening such cutters, the index plates used need have only' half as many notches as there are blades in the cutter head. One set of blades will be sharpened with the plate 24' tilted in one direction about the pins 26and the other set of blades will be sharpened. with the plate 24S tilted in the other direction. f

There is a cover-plate |45 secured to the bracket |130 by screws |46 and' between this plate and the bracket is mounted an arm |50.

The shape ofy this arm is clearly shown in dotted lines in Figure'll. The cover-plate |45 and the bracket |30 are shaped to provide a guide for this arm so that, as it reciprocates, it `will swing about theV center 3|.

On the under-side ofr the arm there is pivotally mounted the index pawl I5I. The pawl |5I' normally rests on the periphery of the. index plate being used at a slight anguiar 'distance from that notch of the' index plate with which the dog. |40' is in engagement (see Figure 4'). The pawl is formed with a fiat cam surface |52. |54 designates a dog which is pivotally mounted by means of the pin |155 on the lock-dog |40 but which is held against movement in one direction about its pivot pin '|55 by a stop-lug |56 which' is 'suitably secured to the' lock-dog |40. As the arm k|50 is moved to` the left from the position shown in Figure 4", the cam surface |52 of the pawl I5I engages the tip of the dog |54. The dog |54 is held against pivotal movement by the stop-lug |56. Therefore, the lock-dog |40'is swung up outV of Ylocking position against the resistance of the spring plunger |42. When the pawl' |51- has moved far enough tothe left to register with that notch |44? of the index plate from which the lock-dog |40' has just been disengaged, the pawl |5|k drops into that notch. The spring-plunger |42, acting through the llock-dog |40 and trip-dog |54;

forces thev pawl' into engagement with the notch".

In the' further movement of the arm |50; tothe left, the pawl' is maintained by friction in engagement with the notch of the index plate. Asl the arm |50 moves on to thev left, therefore,

the pawl rotates the index'plate, thus indexing the cutter.

When the arm |50 has moved-through asuicient angle, the locking-dog |40, which will have been riding on =the periphery of the index plate, will drop into engagement with the next notch of, the plate, thus locking the plate up again. At this instant, the arm |50 will be reversed, `In the return movement of the arm, the pawl |5| will ratchet out of the notch of the indexl plate with which it has been engaged and will Areturn to its normal position shown in Fig. 4,

the dog i 54 being rocked out of the way againstk `the resistance of the coil spring |51, which is attached at one. end to the dog |54 and on its other end to the locking-dog |40.

The arm |50 is reciprocated by fluid-pressure. To this end, thearmfisconnected by a link |60 with the head |65 ora piston rod |66which is securedto a piston |61. This piston |61 reciprocates in a cylinder |68 which is secured to the bracket |30 by screws |69.

The motive huid-such as oil, is admitted to opposite sides of the piston |61 through pipes V|10fand I'iil that thread into the cylinder |68.

The direction of application of the pressure iiuid to the pistonv |61 is controlled by a reciprocable piston cr plunger |12. This piston is mounted to slide in the bore |13 of a casing |14 that is secured in the base of the machine, see Figure 2.

'Ihe piston |12 is reciprocated by a rotary face-cam |15which is keyed to the shaft |20. There is a'bell-crank arm |16 pivotally mounted-by means of the pin |11 upon the frame oi the machine. On one end of this arm there if carried a roller |18 that engages in the track of the cam |15. At its other end the arm |16 is connected by the link |19 with the piston-rod to which the piston |12 is secured. The rod |80 extends upwardly through the coverplate |82 of the casing |14 and through a sleeve or thimble |63 that is suitably secured to this cover-plate.

The pipe lines |10 and ,|1| thread into the casing |14, communicating, respectively, with ducts |85 and |86 formed in the casing. The lines |10 and |1| constitute with the cylinder |88, in which the pitson |61 slides, and the bore |13, in which the piston |12 slides, a normally closed hydraulic system. Thus, when the piston |12 isforced downwardly in the bore, |13 by operation of the cam |15, the fluid in thelower end of the bore |13 is forced out of the bore through the duct |86 and pipe line |1| into the right end of the cylinder |68, forcing vthe piston |61 to the left in its cylinder and the fluid forced out of theleft end of the cylinder will flow through the line |10 and duct |85 into the bore |13, occupying the` space above the now-lowered piston |12.

yLeakage from this system is, however, liable to occur and, too, excessive pressure might be built up in the system were the effective operating faces of the piston |12 and piston |61 and the dimensions of the cylinder |68 and bore |13 not properly balanced so that in either position of the piston |12, the same amount of oil could vbe contained in the system. Through an ingenious arrangement, which will now be described, the system can be replenished if leakage occurs and the building up of excessive pressure in the system is prevented.

The cap or cover-plate |82 of the casingy is so formed as to providea central well or reservoir k |90. This reservoir yis iilledk with oil up to a point just below the top vof the sleeve or spindle` |83, asshown in Figure `3 of the drawings. Thev system is` normally closed against How of oil from the reservoir into the bore |13 by a pair of ball check-valves |9| and |92. yThe valve |9| is held closed r`by spring |93 and the valve |92 is held closed by spring |94.

When pressurev in the system falls below a predetermined minimum,.the valves |9| and |92 are opened by atmospheric pressurel and by the weight on them of the column of oil in the reservoir |90 and by the suctionexerted by the piston or plunger |12 as it moves in. opposite directions. lWhen the piston' |12 moves upwardly, oil can be drawn into the system from the reservoir through thevalve |9| and the duct |95, and when the piston |12 moves downwardly oil can be drawn into the system from the reservoir through the valve |92 and ducts |96 and |85. Thus leakage in the vsystem is replenished.

Relief valves |91 and |98 `are provided to prevent, buildingup of excessive, pressures in the system.` The valve |91 closes the duct |99v that communicates with the` duct 200 which leads from the duct |95. The valve |98 closes the duct 202 which communicates with the duct |96 through the duct 203. The valves |91. and |99 are normally held closed by the coil springs 205 and 206, respectively.. The tension of these springs, respectively, `can be adjusted by threading up the screws 201 and 208.

Excess oil can, therefore, be discharged from the system, in the reciprocation of the-piston |12, through either the valve |91 or |98. When the'valve |91 is opened, the oil is discharged from the duct |99v through the duct 209 into the reservoir |90, while' when the valve |98 is opened, the fluid in the system is discharged from the duct 202 through the duct `2|0 into the reservoir |90.

The stroke of 'the piston-|61, which determines the amount of angular movement of the index plateforrindexing, is adjusted by adjustment of the stop-screw 2|5 (Figure 3). This screw threads into the'cover plate |45 of the bracket |30 andis adapted tor contact with thehead |65 of the piston rod |66to limit the 'movement of the piston rod tothe left. A lock-nut 2|6 is provided to secure the stop screw 2|5 inv any adjusted position. vl f For .wet grinding, the machine is provided with a pump 220, which may be of any suitable construction and which is suitably mounted in the base of the machine (Figure 1). This pump pumps the water or other coolant from the sump or tank22| through suitable piping (not shown),y

to the cutter at the point of engagement of the grinding wheel with the cutter.

The tank or sump 22| is suitably secured to the frame of the machine Vat one side thereof. The coolant falling off the cutter and grinding wheel drops into the trough |3. This trough is formed with an inclined bottom 222 that slopes toward one side of the machine and the.

bearings-221 and 228 in the frame ofthe machine. To this shaft 226 there is secured a bevel pinion 229 which meshes with the bevel gear 230 that is secured to the vertical shaft 23| which carries the impellor orpaddle 232 of the pump 220. The vertical shaft 23| is journaled in the frame of the machine on antifriction bearings 233. v

An automatic stop may be used upon the machine to stop the machine when sharpening operations on a set of blades have been completed. Such a stop is shown at 230 in the drawings (Figures 1 and 2). The stop may be of any suitable type. That shown is of the same construction as the stop described and claimed in the pending application of .George E. Ford, Serial No. 441,694, filed April 4, 1930.

'There is a strap 23| `adjustably secured to theslide81 (Figure l) by means of a bolt 232 which threads yinto the slide and which passes through an, elongated slot 233 in the strap. There is a trip-dog 235 pivotally mounted at 236 upon the strap 23| but held by a stop-lug orother suitable meansagainst pivotal4 move-` ment in one direction on its pin. Each time that the slide 01- moves upwardly, the rtrip-dog 235 `will strike the plunger 238 of the stop 230, ratcheting the stop mechanism forward. `On the down stroke of the slide 8,1, the trip-dog 235 kicks out of the way without operating the plunger 238, for it pivots about its pivot-pin 236. I

When a bevel gear cutter of the usual type is being sharpened, the stop mechanism 230 is initially adjusted to trip after khalf the number of the blades in thev cutter head have been sharpened, that is, after all the blades forY cutting one side tooth surface of a gear blank have been ground. When the automatic stop is tripped the motor `|25 with which the stop is in circuit is stopped.

In the use of the machine, the center 3| is secured.l by the screws 32 in one or other of the sockets 29 or 30, depending v,upon whether a small or a large size cutter isto bev sharpened. A small size index plate 46 and a small guard plate 45 or a large size index plate 56 and a large guard plate 55 are then slipped onto lthe center 3| depending upon the size of thefcutter to be'sharpened. The arbor 35 isr then placed upon the center 3| and secured. to thevguard plate. The cutter tov be i sharpened is `*then clamped on the arbor by the disc 31 and bolt 38. The plate 24 is tilted angularly' about the'pivot pins 26 to vone side or the otherf depending upon which group of `side cuttingl blades is to be sharpened first. The plate 24 carries on its under face a pair of spacedstop-lugs 240 (Figure 1). These'stop lugs engage pins 24|, that are secured'in ears 242 formed integralwith the carriage "l5, to limit the angular tilting movement of theplate 24 in both directions so that the desired amount of side rake will be ground on the blades of the cutter.

The carriage l5 is adjusted on the table I2 by means of the screw I6 to bring the` cutter into position to permit grinding back the blades to the desired depth. The grinding wheel is secured on the spindle E0an`d the grinding wheel head 65 is adjusted longitudinally on the carrier 15 to bring the grinding Wheel into operative relation with the blades. The amount of this adjustment will depend uponr the extent to which the wheel and the blades have been worn backr by repeated use. The carrier15;is,.ad justed angularly on the bracket so as to grind the blades with the proper hook or drag. In the bevel gear field, the front faces of the blades of the cutter have a standard inclination from their tips to their roo-ts and the carrier 15 may therefore be adjusted by bringing the The bracket 85 is then adjusted angularly on n the slide 81 by theadjusting screw |04, ifv a change of setting is desired to dispose the grinding wheel symmetrically of the front faces of the blades being ground. The stop screw 2|5 (Figure 3) is then adjusted to limit the amount of indexing movement of the pawl |5|.

When all of these adjustments have been made, the machine is ready for use and the operator .starts the wheel drive motor by pressing in the start button of a combination start and stop buttony 250 y(Figure 1).. As soon as the wheel is rotatinghe presses in the start button of a combination start and stopvbutton 25| to start the main drive motor |25. The wheel drive motor drives the grinding wheel spindle 50 through thebelt 95 and pulleys 9 6 and 91, as described.` The main drive motor |25 drives the shaft |20 through the wormk |21 and worm wheel |28. This rotates thecams |.|4 and |15 simultaneously. The cam ||4 reciprocates the yslide 81, carrying the grinding wheel across the faces of the blades of the cutter. At one end of the stroke of the slide 81, when the grinding wheel is clear of the cutter, the cam |15 will rock the lever arm |13 (Figure 3) to cause an indexing movement to be imparted to the indexing pawl I5. In-Figure 3, the arm |13V is shown in position just prior tothe indexing movement. `As this arm is rocked from the position shown, the piston |12 is forced downwardly in the bore, |13, forcing the oil in the lower end ofv the bore out through the line |1| into the right endlvof the cylinder |60 to force thepiston |51 tothe left. The oil inthe left end of the cylinder |68 flows out of the cylinder through the line |10 into the upperend of the bore |13 above the descending piston |12. If there is an excess of oil in the system, the relief valve |98 is opened by the pressure in the system and the excess of oil flows out `into the reservoir |90 through the duct 2|0. If there has been leakage from the system, the system is replenished from reservoir |90 through opening ofthe valve |92 by air pressure, gravity,

andthe suction exerted by the downwardly de- 60 scending piston |12.

The movement of the piston |61 tothe left, as just described, causes the pawl |5|, to engage the dog |54 and force the locking-dog y|40 out of locking position. The pawl |5| then drops into engagement with the index plate and rotates the index plate through the angle required `for indexing. The locking-dog |40 Awill ride on the periphery` of the index plate during this movement and when it comes'into registry with the next notch of the plate will drop into engagement therewith, locking the index plate up again. y

4rIhe cams ||4 and |15v will be so shaped relative to oneanother that as soonyas the indexing operation is completed, theslide 01' will be in -cending piston |12.

position in its movement to carry the grinding wheel across the face of the lnew blade which has been indexed into sharpening position. During the passage of the grinding wheel back and forth across this blade, the parts of the index mechanisml will be returned to initial position by reversal of the piston |12 under actuation of the cam |15. The cam causes the arm |16 to be swung again to the position shown in Figure 3, pulling the piston |12 upwardly and forcing the oil in the bore '|13 above the piston out of the bore |13 through the line |10 into the` right end of the cylinder |68. This forces the piston |61 back-,to the right inthe cylinder, pulling the arm |50 and the pawl |5| back to the right. In this movement to the right, the pawl |5| ratchets idly over the index plate and simply kicks the dog |54 out of the way against the resistance vof the spring |51. The oil forced out of the right end of the cylinder |61 flows back through the line |1| into the lower end oi the bore |13, lling up the bore behind the as- If there is an excess of oil in the system, the valve |91 is opened by the pressure and the excess oil flows out through the duct 209 into the reservoir. |90. If there has been leakage from the system, the system is replenished from the reservoir through the valve |9| which is opened by atmospheric pressure, gravity and the suction exerted by the ascending piston or plunger |12.

The machine operates, therefore, to pass the grinding Wheelback and forth once across the front face of a blade of the cutter and then the cutter is indexed to bring a new blade into position. An indexing operation occurs, in other Words, after each reciprocation of the grinding Wheel slide. The cam |15 might be formed, however, so kas to index the cutter at both ends of the stroke of the grinding wheel slide.

If one passage of the grinding wheel back and forth across the blade is considered sufficient to sharpen the blades, the automatic stop 230 can be set to operate after the grinding wheel has been passed across the faces of all of the blades cutting on the same side, namely, after lthe cutter head has beenV indexed through one revolution. If more passagesof the grinding wheel across lthe' faces of the blades are required to sharpen the blades, the automatic stop will be setv accordingly. When one set of blades khas been sharpened, the. operator tilts the cutter head on the pins 26 to bring the blades of the other set into position for sharpening. When these blades have been sharpened, the cutter will have rbeen ground.

c, The automatic stop may be adjusted so as to stop the motor |25 when the grinding wheel is entirely clear of the cutter head so as .tofacilitate quick removal of one cutter from the machine and placing of another.

While the invention has been described in connection with the sharpening of a particular type of cutter and in a particular manner, it ywill be understood that in its broaderY aspects, the invention is not limited to this particular use or construction. This application is intended to cover any adaptation, use, or embodiment of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is: 1. In a machine for, sharpening cutters, a frame, a tool support reciprocable vertically on the frame, a carrier adjustable angularly on said tool support, a tool head Iadjustablevrectilinearly on ysaid carrier in a.l directional; right angles to the axis about which said carrier is adjustable, a. grindingl wheel journaled in said tool head, a carriage adjustable rectilinearly in a horizontal plane on the frame, a work support adjustable angularly on said carriage about a horizontal axis, a work arbor rotatablymounted on said work support and adapted to carryr the cutter to be sharpened, means rfor reciprocatingv said tool support through a distance longenough to pass the grinding wheel across thev facefof a blade of the cutter and then clear-'the cutter, and means for rotatably indexing the work arbor when the grinding wheel is clear ofl the cutter.

2. `In combination, a work support, ga Work arbor journaled'therein, a notched-index plate secured to the work arbor, a locking dog pivotally mounted on said work supportfmeans constant-` ly urging said locking dog into engagement with said notched plate, a trip dog pivotally 'mounted on ysaid locking dog,-meansresiliently holding said trip dog against movement in one direction about its pivot and means positively limiting movementcf said dog in the opposite direction, anarrn movable angularly about the'axis of said work arbor, a pawl pivotally mounted on-s'aid arm and formedwith a cam surface adapted to engage said trip dog tofmove the locking dog out of engagement with the index plate on movement of said armwin vone direction, means for moving said pawl into engagement with the notched plate when. the locking dog is disengaged, and means for periodically oscillating said arm to index the work arbor. l

3. In a machine for vsharpening cutters, a frame, a Work-support and a tool support, one of which is reciprocable on theframa a. grinding wheel journaled on the tool support, a. work head adjustably mountedfon'the work support, a work spindle journaled in the Work head, indexing mechanism for the work spindle, means for actuating said indexingmechanism comprising a cylinder and -a piston reciprocable therein, a second cylinder anda' second piston reciprocable therein, and pipingconnectingthe second cylinder withthe first cylinder, said cylindersI and piping-constituting a normally closedhydraulic system whereby movement of the second piston in opposite directions in its cylinder causes movement of the` first piston in opposite directions in its cylinder,` a...positive stop for limiting movement of the first piston, a reservoir, and valves connecting the hydraulic system withv said reservoir to allow automatically exhaust from or supply to said lsystem when pressure `in the system risesabovev or falls below, respectively, a predetermined operating pressure, ashaft journaled in the frame, a. pair of cams secured to said shaft, means connecting one of said cams to said tool support tov reciprocate the same to pass the grinding wheel across the Work, means connecting the other cam to the second piston toreciprocate the same, and means for rotating said shaft.

4. In a machine forsharpening cutters, a frame, a vtool support movable on the frame, a grinding wheeljournaled in the tool support.

a work support mounted on the frame, a rotatable Work spindle adapted to be secured on said Work support selectively in a plurality of different positions at different distances from said grinding Wheel, said work spindle being adapted to carry different notched index plates, index mechanism comprising means for locking said different index plates against rotation dur- .ing grinding and means for rotating said clifferent index plates, when the locking means is released, to index the Work, means for securing the index mechanism in a plurality of diierent positions on the Work support to permit cooperation ofl said index mechanism With index plates carried by the Work spindle in different positions of the Work spindle, means for-actuating said index mechanism, and means for moving the tool support to effect the. grinding operation.

5. In a machine-for sharpening cutters, a frame, a tool support movable on the frame, a grinding wheel journaled in the tool support, a Work support mounted on the frame and having a plurality of openings therein, a Work spindle adapted to be secured to the work support selectively in said different openings, a member mounted on said Work spindle and rotatable to index the work, means adapted to cooperate with said member to rotate the same, a bracket on which said last named means is mounted,

means for securing said bracket in different positions on the Work support in correspondence With diierent positions of location of said Work spindle, means for moving the tool support to effect the grinding operation, and means` for actuating said index mechanism in all of its different positions.

6. In a machine for sharpening cutters, a frame, a tool support mounted on the frame, a grinding Wheel journaled in the tool support, a Work support mounted on the frame and having a plurality of sockets formed therein land havM ing a plurality of arcuate slots formed therein concentric, respectively, to the different sockets, a Work spindle adapted to be secured selectively in said different sockets and adapted to carry different sized index plates, indexing mechanism adapted to cooperate with any of the indexy plates, a bracket on which said index mechanism is mounted, means for securing said bracket in different slots of said Work support in accordance with the location of the work spindle, 

